*{
    margin: 0;
    padding: 0;
    list-style: none;
    text-decoration: none;
    font-family: sans-serif;
}
.container{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
}
.menu{
    width: 300px;
    border-radius: 5px;
    overflow: hidden;
}
.item{
    border-top: 2px solid #1abc9c;
    overflow: hidden;
}
.btn{
    display: block;
    background-color: #2980b9;
    text-transform: capitalize;
    color: #fff;
    font-size: 18px;
    padding: 14px 24px;
    position: relative;
}
.btn::before{
    content: '';
    display: block;
    width: 14px;
    height: 14px;
    position: absolute;
    left: 25px;
    bottom: -7px;
    background-color: #2980b9;
    transform: rotate(45deg);
}
.btn span{
    margin-right: 10px;
}
.smenu{
    background-color: #333;
    overflow: hidden;
    transition: max-height .3s;
    max-height: 0;
}
.smenu a{
    
    color: #fff;
    display: block;
    padding: 14px 20px;
    position: relative;
    margin: 4px 0;
}
.smenu a::before{
    content: '';
    position: absolute;
    width: 4px;
    height: 100%;
    background-color: #2980b9;
    left: 0;
    top: 0;
    opacity: 0;
    transition: .3s;
}
.smenu a:hover::before{
    opacity: 1;
}
.item:target .smenu{
    max-height: 10rem;
}